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RE: expanding a list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg42610] RE: [mg42593] expanding a list
  • From: "Harvey P. Dale" <hpd1 at nyu.edu>
  • Date: Fri, 18 Jul 2003 05:25:03 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Alan:

            This should do it:

Flatten[Table[#[[1]],{#[[2]]}]&/@Transpose[{plist,flist}]]

            Best,

            Harvey

Harvey P. Dale

University Professor of Philanthropy and the Law

Director, National Center on Philanthropy and the Law

New York University School of Law

Room 206A

110 West 3rd Street

New York, N.Y. 10012-1074



-----Original Message-----
From: Alan Kelly [mailto:Alan.Kelly at tcd.ie]
To: mathgroup at smc.vnet.net
Subject: [mg42610] [mg42593] expanding a list



Hi all,

I believe that this is a rather elementary question, but I am not

aware of a simple, elegant and efficient solution. I have searched

the MathGroup archive, but with no success.



I have two lists - both of the same length.  The first contains a

list of probabilities. For example, suppose the list length is 4

(although in practice it would be much longer) and is of the

following form:

plist = {0.252, 0.252, 0.257, 0.235}.

The second contains a  list of integers:

flist = {7,5,6,4}.

I wish to take the first element of plist and replicate that value

using the first element of flist.  Similarly for the remaining

elements.

I should finish with a list of length 7+5+6+4 or 22.

Any suggestion please.

Many thanks,

Alan Kelly

Trinity College Dublin




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